There is a demand to shorten search time in a memory system which executes a key-value search. Thereby, a solid state drive (SSD) accessible fast is used as the memory system which executes the key-value search. For example, the solid state drive (SSD) includes a nonvolatile semiconductor memory such as a NAND flash memory. The NAND flash memory includes a plurality of blocks (physical blocks). The plurality of blocks include a plurality of memory cells arranged at crossing points of word lines and bit lines.